EP0595670B1 - Hydraulic command device for brake system of a vehicle with two hydraulic brake circuits - Google Patents

Hydraulic command device for brake system of a vehicle with two hydraulic brake circuits Download PDF

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Publication number
EP0595670B1
EP0595670B1 EP19930402392 EP93402392A EP0595670B1 EP 0595670 B1 EP0595670 B1 EP 0595670B1 EP 19930402392 EP19930402392 EP 19930402392 EP 93402392 A EP93402392 A EP 93402392A EP 0595670 B1 EP0595670 B1 EP 0595670B1
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EP
European Patent Office
Prior art keywords
slide valve
piston
braking
pressure
spring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19930402392
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German (de)
French (fr)
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EP0595670A1 (en
Inventor
Claude Perrin
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Automobiles Peugeot SA
Automobiles Citroen SA
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Automobiles Peugeot SA
Automobiles Citroen SA
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Publication of EP0595670A1 publication Critical patent/EP0595670A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
    • B60T13/14—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid using accumulators or reservoirs fed by pumps
    • B60T13/142—Systems with master cylinder
    • B60T13/147—In combination with distributor valve

Definitions

  • the present invention relates to a hydraulic actuation device for a braking installation of a motor vehicle comprising two hydraulic braking circuits, provided with means for hydraulic amplification of the braking force.
  • a hydraulic actuating device for a braking installation with two independent hydraulic circuits of the type comprising a body comprising a piston, actuated by a pedal brake, slidably mounted in a first bore formed in the body, a pressure regulating drawer slidably mounted in a second bore formed in the body coaxially with the first bore, the bores having their ends close in communication, the piston and the delimiting drawer, on the one hand, between their close ends, a central pressure chamber communicating with a first braking circuit, and on the other hand, at their opposite ends, two end chambers communicating with each other and with the second braking circuit, the drawer being movable between a rest position towards which it is spring-loaded and in which it puts in com munication the end chambers with a reservoir of liquid at normal pressure, and a regulation position in which it communicates the end chambers and the second braking circuit with a source of high pressure liquid greater than normal pressure.
  • the displacement of the piston under the action of the brake pedal first causes a rise in pressure in the first circuit of braking and then, when the pressure is sufficient, a displacement of the slide causing a rise in pressure in the second circuit. Consequently, when the brake pedal is actuated by the driver, the pressure build-up in the two brake circuits is not simultaneous.
  • the object of the invention is to provide a braking device with two braking circuits in which the pressure rise in the two braking circuits takes place simultaneously when the brake pedal is actuated by the driver, this device being moreover simpler. to manufacture than those known in the state of the art.
  • the subject of the invention is a hydraulic actuating device for a braking installation of a motor vehicle of the aforementioned type, characterized in that the pressure regulation drawer comprises means for bringing a reservoir of communication into communication. liquid at normal pressure with the central chamber, in the rest position of the drawer.
  • the hydraulic actuation device according to the invention represented in FIG. 1, designated by the general reference 10, is intended to be incorporated in a braking installation of a motor vehicle comprising two braking circuits C1, C2.
  • This device is provided with hydraulic amplification means of the braking force. It will be called subsequently "brake booster".
  • FIG. 1 also shows a hydraulic unit of known type, designated by the general reference 11, connected to the braking installation.
  • This hydraulic unit 11 comprises two reservoirs R1, R2 of brake fluid at normal pressure, for example at atmospheric pressure, connected respectively to the braking circuits C1, C2 by conventional means which will be described later.
  • the brake fluid is of known type and includes, for example, mineral oil.
  • the hydraulic unit 11 also includes a source SP of high pressure brake fluid, higher than the normal pressure of the fluid, comprising the reservoir R2, a pump P, a non-return valve C and a pressure accumulator AP.
  • a source SP of high pressure brake fluid higher than the normal pressure of the fluid, comprising the reservoir R2, a pump P, a non-return valve C and a pressure accumulator AP.
  • the source SP of high pressure liquid is connected by known means, which will be described later, to the brake booster 10.
  • the brake booster 10 comprises a body 12 in which are axially arranged two coaxial bores 14, 16, of substantially identical diameters, having their ends close in communication. These close ends are connected together by an annular recess 18 formed in the body 12.
  • the seal between the plugs 24, 26 and the internal surface of the holes 20, 22 is obtained in a conventional manner by means of O-rings 32, 34 arranged between these elements.
  • a piston 36 actuated by a brake pedal 37, is slidably mounted in the first bore 14. Furthermore, a pressure regulating drawer 38 is slidably mounted in the second bore 16.
  • the central chamber 40 and the two end chambers 42, 44 contain brake fluid coming from the reservoirs R1, R2.
  • the central chamber 40 is connected via a conduit 46 formed in the body 12 to a first braking circuit C1.
  • the duct 46 opens into the recess 18 disposed in the body 12 so as to be in communication with the chamber 40 independently of the positions of the piston 36 and of the drawer 38.
  • the end chambers 42, 44 are connected to each other and to the second braking circuit C2 by three conduits 48-52, formed in the body 12, communicating with one another.
  • This piston 36 comprises two sealing cups 54, 56 of known type, arranged at its ends and fixed to the piston by known means.
  • the end of the piston 36 opposite the end chamber 42 (on the right when considering FIG. 1) is extended by a rod 58, passing through the plug 24, connecting with a push rod 60 connected by means known to the brake pedal 37.
  • the rod 58 and the rod 60 are connected together by interlocking their connection ends.
  • the seal between the plug 24 and the connecting rod 58 is provided conventionally by an O-ring 61 disposed between these elements.
  • the free end of the rod 58 carries a spring 62 for returning the piston 36 to the rest position.
  • the spring 62 is mounted between two cups 64, 66 forming seats, the first being integral with the rod 58 and the second being integral with the body 12.
  • the piston 36 also includes a positioning flange 67 intended to cooperate by abutment with a complementary projection 68 of the plug 24 to maintain the piston 36 in the rest position.
  • a protective bellows 69 covers the return spring 62 and its support means.
  • the end of the piston 36 opposite the central chamber 40 (on the left when considering FIG. 1) comprises elastic means 70 for pushing the drawer 38.
  • These means comprise a prestressed spring 72 mounted between two cups 74, 76 forming seats, the first being integral with the piston 36 and the second being mounted sliding on a support rod 78 fixed by one end to the piston 36, coaxial with the latter.
  • the free end of the rod 78 is provided with a collar 80 forming a retaining stop for the sliding cup 76 so as to maintain the spring 72 in precompression.
  • the sliding cup 76 is provided with openings 82 for passing brake fluid.
  • the peripheral edge of the cup 76 is intended to cooperate with a shoulder 83 of complementary shape formed in the external peripheral surface of the corresponding end of the drawer 38.
  • the drawer 38 is resiliently biased in the rest position by a return spring 84 held in compression between two parts forming a seat 86, 88 secured respectively to the plug 26 and to the corresponding end of the drawer 38.
  • the calibration of the return spring 84 is lower than that of the thrust spring 72.
  • a washer 90 for positioning the drawer 38 in the rest position is fixed by known means on the end of the drawer 38 opposite the chamber 44 and is intended to cooperate with a shoulder 92 formed in the body 12 at the junction of the bore 16 and bore 22.
  • the drawer 38 has a blind hole 94, stepped, formed coaxially with the drawer.
  • the hole 94 communicates through its open end with the central chamber 40.
  • the dimensions of the hole 94 are adapted, on the one hand, so that it can form a housing for the free end of the support rod 80 when the piston 36 and the drawer 38 move relative to each other, and secondly to lighten the drawer 38.
  • the hole 94 is connected by at least one bore 96 made radially in the drawer 38 to a first groove annular 98 formed in the peripheral surface of the drawer 38.
  • the drawer 38 also includes a second annular groove 100, of greater width than the groove 96, formed on its peripheral surface.
  • the groove 100 has a width adapted so that, independently of the position of the drawer 38, it communicates with a conduit 110, formed in the body 12, connected to the end chambers 42, 44 and to the second braking circuit C2 by the intermediate of conduits 48-52.
  • the first annular groove 98 communicates with a conduit 102 connected by known means 104 to the tank R1
  • the second annular groove 100 communicates with a conduit 106 formed in the body 12 and connected by known means 108 to the reservoir R2.
  • the first groove 98 is isolated from the conduit 102 for connection to the reservoir R1
  • the second groove 100 is, on the one hand, isolated of the connection conduit 106 to the reservoir R2, and on the other hand placed in communication with a conduit 112, formed in the body 12, connected by known means 114 to the source SP of high pressure liquid.
  • the driver actuates the brake pedal 37 and moves the piston 36 axially towards the central chamber 40, by means of the push rod 60.
  • the thrust means 70 urge the drawer 38 against the return force of the spring 84 and displaces the latter axially to the left when considering FIG. 1.
  • the displacement of the drawer 38 firstly causes the simultaneous closing of the conduits 102, 106 for connection to the reservoirs R1, R2 and then the placing of the second groove 100 in communication with the conduit 112 for connection to the source SP of high pressure liquid.
  • the reservoir R1 being isolated from the central chamber 40, the pressure of the liquid contained in this chamber and in the first braking circuit C1 increases.
  • the slide 38 In the active braking position, the slide 38 allows, on the one hand to supply pressure to the second braking circuit, and on the other hand to assist the braking force of the driver.
  • the second groove 100 being supplied with high pressure liquid, the pressure of the liquid contained in the second braking circuit C2, communicating with the groove 100, increases.
  • the pressure of the liquid in the second braking circuit C2 is also that of the liquid contained in the end chambers 42 and 44 communicating with the circuit C2.
  • the pressure of the liquid in the chamber 42 acts on the piston 36, in the direction of braking, so as to amplify the force supplied by the driver on the brake pedal.
  • the width and the position of the two peripheral grooves 98,100 of the drawer 38 are adapted so that, on the one hand the stroke of the drawer making it possible to isolate the conduits 102 and 106, and on the other hand the stroke of the drawer making it possible to put in communication the second groove 100 with the conduit 112, are very weak. In this way, after a very small displacement of the drawer, the latter is in equilibrium under the action of compensating forces. These forces are on the one hand, on the side of the chamber 44, the force due to the pressure of the liquid from the second braking circuit C2 and the return force of the spring 84, and on the other hand, on the side of the chamber 40, the force due to the pressure of the liquid from the first circuit brake C1 and spring 72 pushing force.
  • the calibration difference of the two springs 72, 84 is such that the pressure difference on either side of the slide 38 does not exceed 2 bar during intense braking.
  • the displacement of the piston 36 is proportional to the liquid consumption of the first braking circuit C1, that is to say proportional to the displacement of liquid due to the stroke of the pistons conventionally mounted in the organs of braking arranged in the vicinity of the vehicle wheels and supplied by this circuit.
  • the elastic pushing means 70 comprise a spring 72 carried by a support 78A forming a tube, held by one of its ends on the piston 36, coaxial with the latter.
  • the fixing end of the support 78A comprises a flange 116 and is engaged to the bottom of an axial recess 117 formed in the end of the piston 36 opposite the central chamber 40.
  • a tip 118 is screwed onto the free end of the support 78A.
  • This nozzle 118 comprises a circular head 120 with a diameter greater than the external diameter of the support 78A so as to form an end shoulder of the support 78A.
  • the spring 72 is prestressed between two seats, the first being formed by the flange 116 of the support 78A and the second being formed by a sleeve 122, provided at one of its ends with a flange 124 intended to cooperate with the spring, slidingly mounted on support 78A.
  • the flange 124 is also intended to cooperate with a shoulder 126 formed in the internal surface of the axial hole 94 of the drawer 38.
  • the stroke of the sleeve 122 is limited to the free end of the support 78A by the shoulder formed by the head 120 of the end piece 118.
  • the support 78A and the end piece 118 have holes 128,130 allowing the passage of the brake oil between the hole 94 and the central chamber 40.
  • the hole 94 of the drawer 38 forms a housing for the support 78A of the pushing means 70.
  • the two tanks of the hydraulic unit can be replaced by a single tank.
  • the invention has many advantages.
  • the pressure regulation drawer simultaneously isolates the connection lines to the brake circuit reservoirs and therefore achieves a simultaneous pressure rise in the two brake circuits when the brake pedal is actuated.
  • the brake booster is easy to manufacture since the bores in which the piston and the pressure regulating slide slide are coaxial and of substantially identical diameters. These bores can be drilled in a single machining operation. However, the finishing operations can be carried out differently depending on whether the bore is intended to receive the piston or the pressure regulating slide.

Description

La présente invention concerne un dispositif hydraulique d'actionnement pour une installation de freinage d'un véhicule automobile comportant deux circuits hydrauliques de freinage, muni de moyens d'amplification hydraulique de l'effort de freinage.The present invention relates to a hydraulic actuation device for a braking installation of a motor vehicle comprising two hydraulic braking circuits, provided with means for hydraulic amplification of the braking force.

De façon classique, la sécurité du freinage est accrue par l'utilisation de deux circuits de freinage totalement indépendants alimentés par une commande unique (pédale de frein).Conventionally, braking safety is increased by the use of two completely independent braking circuits supplied by a single control (brake pedal).

On connaît déjà dans l'état de la technique, notamment de FR-2 303 691, un dispositif hydraulique d'actionnement pour une installation de freinage à deux circuits hydrauliques indépendants, du type comportant un corps comprenant un piston, actionné par une pédale de frein, monté coulissant dans un premier alésage ménagé dans le corps, un tiroir de régulation de pression monté coulissant dans un second alésage ménagé dans le corps coaxialement au premier alésage, les alésages ayant leurs extrémités rapprochées en communication, le piston et le tiroir délimitant, d'une part, entre leurs extrémités rapprochées, une chambre centrale de pression communiquant avec un premier circuit de freinage, et d'autre part, à leurs extrémités opposées, deux chambres d'extrémité communiquant entre elles et avec le second circuit de freinage, le tiroir étant déplaçable entre une position de repos vers laquelle il est rappelé élastiquement et dans laquelle il met en communication les chambres d'extrémité avec un réservoir de liquide à pression normale, et une position de régulation dans laquelle il met en communication les chambres d'extrémité et le second circuit de freinage avec une source de liquide haute pression supérieure à la pression normale.Already known in the prior art, in particular from FR-2 303 691, a hydraulic actuating device for a braking installation with two independent hydraulic circuits, of the type comprising a body comprising a piston, actuated by a pedal brake, slidably mounted in a first bore formed in the body, a pressure regulating drawer slidably mounted in a second bore formed in the body coaxially with the first bore, the bores having their ends close in communication, the piston and the delimiting drawer, on the one hand, between their close ends, a central pressure chamber communicating with a first braking circuit, and on the other hand, at their opposite ends, two end chambers communicating with each other and with the second braking circuit, the drawer being movable between a rest position towards which it is spring-loaded and in which it puts in com munication the end chambers with a reservoir of liquid at normal pressure, and a regulation position in which it communicates the end chambers and the second braking circuit with a source of high pressure liquid greater than normal pressure.

Dans ce type de dispositif, le déplacement du piston sous l'action de la pédale de frein provoque d'abord une montée en pression dans le premier circuit de freinage et ensuite, lorsque la pression est suffisante, un déplacement du tiroir provoquant une montée en pression dans le second circuit. Par conséquent, lorsque la pédale de frein est actionnée par le conducteur, la montée en pression dans les deux circuits de freinage n'est pas simultanée.In this type of device, the displacement of the piston under the action of the brake pedal first causes a rise in pressure in the first circuit of braking and then, when the pressure is sufficient, a displacement of the slide causing a rise in pressure in the second circuit. Consequently, when the brake pedal is actuated by the driver, the pressure build-up in the two brake circuits is not simultaneous.

L'invention a pour but de fournir un dispositif de freinage à deux circuits de freinage dans lequel la montée en pression dans les deux circuits de freinage se fasse simultanément lorsque la pédale de frein est actionnée par le conducteur, ce dispositif étant par ailleurs plus simple à fabriquer que ceux connus dans l'état de la technique.The object of the invention is to provide a braking device with two braking circuits in which the pressure rise in the two braking circuits takes place simultaneously when the brake pedal is actuated by the driver, this device being moreover simpler. to manufacture than those known in the state of the art.

A cet effet l'invention a pour objet un dispositif hydraulique d'actionnement pour une installation de freinage d'un véhicule automobile du type précité caractérisé en ce que le tiroir de régulation de pression comporte des moyens de mise en communication d'un réservoir de liquide à pression normale avec la chambre centrale, en position de repos du tiroir.To this end, the subject of the invention is a hydraulic actuating device for a braking installation of a motor vehicle of the aforementioned type, characterized in that the pressure regulation drawer comprises means for bringing a reservoir of communication into communication. liquid at normal pressure with the central chamber, in the rest position of the drawer.

Suivant d'autres caractéristiques de cette invention:

  • les moyens de communication comprennent un trou sensiblement axial ménagé dans le tiroir, débouchant dans la chambre centrale, relié par au moins un perçage sensiblement radial ménagé dans le tiroir à une gorge annulaire ménagée dans la surface périphérique du tiroir et destinée à être mise en communication avec un conduit relié au réservoir de liquide à pression normale, en position de repos du tiroir
  • le piston comporte des moyens élastiques de poussée destinés à solliciter le tiroir à l'encontre des moyens de rappel de ce tiroir en position de repos ;
  • les moyens élastiques de poussée comprennent un ressort précontraint, de tarage supérieur au tarage d'un ressort des moyens de rappel du tiroir en position de repos ;
  • le ressort précontraint est disposé entre deux sièges, le premier siège étant solidaire du piston, le second siège étant monté coulissant sur un support formant tige solidaire du piston, l'extrémité libre de la tige comportant une collerette destinée à coopérer par butée avec le siège coulissant pour maintenir le ressort en précompression, le siège coulissant coopérant avec un épaulement ménagé dans la surface périphérique externe du tiroir, ou bien, le ressort précontraint est disposé entre deux sièges, le premier siège étant solidaire du piston et formé à une extrémité d'un support tubulaire, le second siège étant monté coulissant sur ce support tubulaire, l'extrémité libre du support comportant un embout formant butée destiné à coopérer avec le siège coulissant pour maintenir le ressort en précompression, le siège coulissant coopérant avec un épaulement ménagé dans la surface du tiroir délimitant le trou sensiblement axial ;
  • le trou sensiblement axial du tiroir forme logement pour le support de ressort précontraint, lorsque le tiroir et le piston se déplacent l'un par rapport à l'autre au cours d'une opération de freinage ;
  • les deux alésages coaxiaux ont des diamètres sensiblement identiques.
According to other characteristics of this invention:
  • the communication means comprise a substantially axial hole formed in the drawer, opening into the central chamber, connected by at least one substantially radial hole formed in the drawer to an annular groove formed in the peripheral surface of the drawer and intended to be placed in communication with a duct connected to the liquid tank at normal pressure, in the drawer rest position
  • the piston comprises elastic thrust means intended to urge the drawer against the return means of this drawer in the rest position;
  • the elastic thrust means comprise a prestressed spring, with a calibration greater than the calibration of a spring of the drawer return means in the rest position;
  • the prestressed spring is disposed between two seats, the first seat being integral with the piston, the second seat being slidably mounted on a support forming a rod integral with the piston, the free end of the rod comprising a flange intended to cooperate by abutment with the seat sliding to maintain the spring in precompression, the sliding seat cooperating with a shoulder formed in the external peripheral surface of the drawer, or else, the prestressed spring is disposed between two seats, the first seat being integral with the piston and formed at one end of a tubular support, the second seat being slidably mounted on this tubular support, the free end of the support comprising an end piece forming a stop intended to cooperate with the sliding seat to maintain the spring in precompression, the sliding seat cooperating with a shoulder formed in the surface of the drawer delimiting the substantially axial hole;
  • the substantially axial hole of the drawer forms a housing for the prestressed spring support, when the drawer and the piston move relative to each other during a braking operation;
  • the two coaxial bores have substantially identical diameters.

Des exemples de réalisation de l'invention seront décrits ci-dessous en regard des figures annexées dans lesquelles :

  • la figure 1 est une vue en coupe longitudinale d'un dispositif selon l'invention, montrant le piston et le tiroir selon un premier mode de réalisation;
  • la figure 2 est une vue de détail de la figure 1, montrant le piston et le tiroir selon un second mode de réalisation.
Examples of embodiments of the invention will be described below with reference to the appended figures in which:
  • Figure 1 is a longitudinal sectional view of a device according to the invention, showing the piston and the drawer according to a first embodiment;
  • Figure 2 is a detail view of Figure 1 showing the piston and the drawer according to a second embodiment.

Le dispositif hydraulique d'actionnement selon l'invention représenté à la figure 1, désigné par la référence générale 10, est destiné à être incorporé dans une installation de freinage d'un véhicule automobile comportant deux circuits de freinage C1,C2. Ce dispositif est muni de moyens d'amplification hydraulique de l'effort de freinage. Il sera appelé par la suite "servofrein".The hydraulic actuation device according to the invention represented in FIG. 1, designated by the general reference 10, is intended to be incorporated in a braking installation of a motor vehicle comprising two braking circuits C1, C2. This device is provided with hydraulic amplification means of the braking force. It will be called subsequently "brake booster".

On a également représenté à la figure 1 une centrale hydraulique de type connu, désignée par la référence générale 11, raccordée à l'installation de freinage.FIG. 1 also shows a hydraulic unit of known type, designated by the general reference 11, connected to the braking installation.

Cette centrale hydraulique 11 comprend deux réservoirs R1,R2 de liquide de frein à une pression normale, par exemple à la pression atmosphérique, raccordés respectivement aux circuits de freinage C1,C2 par des moyens classiques qui seront décrits ultérieurement.This hydraulic unit 11 comprises two reservoirs R1, R2 of brake fluid at normal pressure, for example at atmospheric pressure, connected respectively to the braking circuits C1, C2 by conventional means which will be described later.

Le liquide de frein est de type connu et comprend par exemple de l'huile minérale.The brake fluid is of known type and includes, for example, mineral oil.

La centrale hydraulique 11 comporte également une source SP de liquide de frein haute pression, supérieure à la pression normale du liquide, comprenant le réservoir R2, une pompe P, un clapet anti-retour C et un accumulateur de pression AP.The hydraulic unit 11 also includes a source SP of high pressure brake fluid, higher than the normal pressure of the fluid, comprising the reservoir R2, a pump P, a non-return valve C and a pressure accumulator AP.

La source SP de liquide haute pression est raccordée par des moyens connus, qui seront décrits ultérieurement, au servofrein 10.The source SP of high pressure liquid is connected by known means, which will be described later, to the brake booster 10.

Le servofrein 10 comporte un corps 12 dans lequel sont ménagés axialement deux alésages 14,16 coaxiaux, de diamètres sensiblement identiques, ayant leurs extrémités rapprochées en communication. Ces extrémités rapprochées sont reliées entre elles par un évidement 18 annulaire ménagé dans le corps 12.The brake booster 10 comprises a body 12 in which are axially arranged two coaxial bores 14, 16, of substantially identical diameters, having their ends close in communication. These close ends are connected together by an annular recess 18 formed in the body 12.

Les extrémités opposées entre elles des alésages 14,16 débouchent respectivement dans des perçages cylindriques 20,22 ménagés dans le corps 12 coaxialement aux alésages 14,16. Ces perçages 20,22 sont obturés à leurs extrémités opposées aux alésages 14,16 par des bouchons 24,26 bloqués de façon connue sur le corps 12, par exemple au moyen de joncs annulaires 28,30.The opposite ends of the bores 14, 16 open respectively into cylindrical bores 20.22 formed in the body 12 coaxially with the bores 14.16. These holes 20, 22 are closed at their ends opposite the bores 14, 16 by plugs 24, 26 blocked in a known manner on the body 12, for example by means of annular rods 28, 30.

L'étanchéité entre les bouchons 24,26 et la surface interne des perçages 20,22 est obtenue de façon classique au moyen de joints toriques 32,34 disposés entre ces éléments.The seal between the plugs 24, 26 and the internal surface of the holes 20, 22 is obtained in a conventional manner by means of O-rings 32, 34 arranged between these elements.

Un piston 36, actionné par une pédale de frein 37, est monté coulissant dans le premier alésage 14. Par ailleurs, un tiroir 38 de régulation de pression est monté coulissant dans le second alésage 16.A piston 36, actuated by a brake pedal 37, is slidably mounted in the first bore 14. Furthermore, a pressure regulating drawer 38 is slidably mounted in the second bore 16.

Les extrémités rapprochées du piston 36 et du tiroir 38 délimitent, à la jonction des alésages 14,16, une chambre centrale de pression 40. L'extrémité du piston 36 en regard du perçage 20 délimite une première chambre d'extrémité 42 et l'extrémité du tiroir 38 en regard du perçage 22 délimite une seconde chambre d'extrémité 44.The close ends of the piston 36 and of the slide 38 delimit, at the junction of the bores 14, 16, a central pressure chamber 40. The end of the piston 36 opposite the bore 20 delimits a first end chamber 42 and the end of the drawer 38 opposite the bore 22 delimits a second end chamber 44.

La chambre centrale 40 et les deux chambres d'extrémité 42,44 contiennent du liquide de frein provenant des réservoirs R1,R2.The central chamber 40 and the two end chambers 42, 44 contain brake fluid coming from the reservoirs R1, R2.

La chambre centrale 40 est reliée par l'intermédiaire d'un conduit 46 ménagé dans le corps 12 à un premier circuit de freinage C1. Le conduit 46 débouche dans l'évidement 18 disposé dans le corps 12 de manière à être en communication avec la chambre 40 indépendamment des positions du piston 36 et du tiroir 38.The central chamber 40 is connected via a conduit 46 formed in the body 12 to a first braking circuit C1. The duct 46 opens into the recess 18 disposed in the body 12 so as to be in communication with the chamber 40 independently of the positions of the piston 36 and of the drawer 38.

Les chambres d'extrémité 42,44 sont raccordées entre elles et au second circuit de freinage C2 par trois conduits 48-52, ménagés dans le corps 12, communiquant entre eux.The end chambers 42, 44 are connected to each other and to the second braking circuit C2 by three conduits 48-52, formed in the body 12, communicating with one another.

On décrira maintenant le piston 36 et le tiroir 38 de régulation de pression plus en détail suivant un premier mode de réalisation.We will now describe the piston 36 and the pressure regulating slide 38 in more detail according to a first embodiment.

Ce piston 36 comporte deux coupelles d'étanchéité 54,56 de type connu, disposées à ses extrémités et fixées sur le piston par des moyens connus.This piston 36 comprises two sealing cups 54, 56 of known type, arranged at its ends and fixed to the piston by known means.

L'extrémité du piston 36 en regard de la chambre d'extrémité 42 (à droite en considérant la figure 1) est prolongée par une tige 58, traversant le bouchon 24, de liaison avec une tringle de poussée 60 reliée par des moyens connus à la pédale de frein 37.The end of the piston 36 opposite the end chamber 42 (on the right when considering FIG. 1) is extended by a rod 58, passing through the plug 24, connecting with a push rod 60 connected by means known to the brake pedal 37.

La tige 58 et la tringle 60 sont reliées entre elles par emboîtement de leurs extrémités de liaison.The rod 58 and the rod 60 are connected together by interlocking their connection ends.

L'étanchéité entre le bouchon 24 et la tige 58 de raccordement est assurée de façon classique par un joint torique 61 disposé entre ces éléments.The seal between the plug 24 and the connecting rod 58 is provided conventionally by an O-ring 61 disposed between these elements.

L'extrémité libre de la tige 58 porte un ressort 62 de rappel du piston 36 en position de repos. Le ressort 62 est monté entre deux coupelles 64, 66 formant sièges, la première étant solidaire de la tige 58 et la seconde étant solidaire du corps 12.The free end of the rod 58 carries a spring 62 for returning the piston 36 to the rest position. The spring 62 is mounted between two cups 64, 66 forming seats, the first being integral with the rod 58 and the second being integral with the body 12.

Le piston 36 comporte également une collerette de positionnement 67 destinée à coopérer par butée avec une saillie complémentaire 68 du bouchon 24 pour maintenir le piston 36 en position de repos.The piston 36 also includes a positioning flange 67 intended to cooperate by abutment with a complementary projection 68 of the plug 24 to maintain the piston 36 in the rest position.

Un soufflet de protection 69 dont les extrémités sont fixées respectivement sur le corps 12 et la tringle de poussée 60, recouvre le ressort 62 de rappel et ses moyens de support.A protective bellows 69, the ends of which are fixed respectively to the body 12 and the push rod 60, covers the return spring 62 and its support means.

L'extrémité du piston 36 en regard de la chambre centrale 40 (à gauche en considérant la figure 1) comporte des moyens élastiques 70 de poussée du tiroir 38. Ces moyens comprennent un ressort 72 précontraint monté entre deux coupelles 74,76 formant sièges, la première étant solidaire du piston 36 et la seconde étant montée coulissante sur une tige support 78 fixée par une extrémité sur le piston 36, coaxialement à ce dernier. L'extrémité libre de la tige 78 est munie d'une collerette 80 formant butée de retenue de la coupelle coulissante 76 de manière à maintenir le ressort 72 en précompression.The end of the piston 36 opposite the central chamber 40 (on the left when considering FIG. 1) comprises elastic means 70 for pushing the drawer 38. These means comprise a prestressed spring 72 mounted between two cups 74, 76 forming seats, the first being integral with the piston 36 and the second being mounted sliding on a support rod 78 fixed by one end to the piston 36, coaxial with the latter. The free end of the rod 78 is provided with a collar 80 forming a retaining stop for the sliding cup 76 so as to maintain the spring 72 in precompression.

La coupelle coulissante 76 est munie d'ouvertures 82 de passage de liquide de frein.The sliding cup 76 is provided with openings 82 for passing brake fluid.

Le bord périphérique de la coupelle 76 est destiné à coopérer avec un épaulement 83 de forme complémentaire ménagé dans la surface périphérique externe de l'extrémité correspondante du tiroir 38.The peripheral edge of the cup 76 is intended to cooperate with a shoulder 83 of complementary shape formed in the external peripheral surface of the corresponding end of the drawer 38.

Le tiroir 38 est sollicité élastiquement en position de repos par un ressort de rappel 84 maintenu en compression entre deux parties formant siège 86,88 solidaires respectivement du bouchon 26 et de l'extrémité correspondante du tiroir 38.The drawer 38 is resiliently biased in the rest position by a return spring 84 held in compression between two parts forming a seat 86, 88 secured respectively to the plug 26 and to the corresponding end of the drawer 38.

Le tarage du ressort de rappel 84 est plus faible que celui du ressort de poussée 72.The calibration of the return spring 84 is lower than that of the thrust spring 72.

Une rondelle 90 de positionnement du tiroir 38 en position de repos est fixée par des moyens connus sur l'extrémité du tiroir 38 en regard de la chambre 44 et est destinée à coopérer avec un épaulement 92 ménagé dans le corps 12 à la jonction de l'alésage 16 et du perçage 22.A washer 90 for positioning the drawer 38 in the rest position is fixed by known means on the end of the drawer 38 opposite the chamber 44 and is intended to cooperate with a shoulder 92 formed in the body 12 at the junction of the bore 16 and bore 22.

Le tiroir 38 comporte un trou borgne 94, étagé, ménagé coaxialement au tiroir.The drawer 38 has a blind hole 94, stepped, formed coaxially with the drawer.

Le trou 94 communique par son extrémité ouverte avec la chambre centrale 40.The hole 94 communicates through its open end with the central chamber 40.

Les dimensions du trou 94 sont adaptées, d'une part pour qu'il puisse former un logement pour l'extrémité libre de la tige support 80 lorsque le piston 36 et le tiroir 38 se déplacent l'un par rapport à l'autre, et d'autre part pour alléger le tiroir 38.The dimensions of the hole 94 are adapted, on the one hand, so that it can form a housing for the free end of the support rod 80 when the piston 36 and the drawer 38 move relative to each other, and secondly to lighten the drawer 38.

Le trou 94 est relié par au moins un perçage 96 ménagé radialement dans le tiroir 38 à une première gorge annulaire 98 ménagée dans la surface périphérique du tiroir 38.The hole 94 is connected by at least one bore 96 made radially in the drawer 38 to a first groove annular 98 formed in the peripheral surface of the drawer 38.

Le tiroir 38 comporte également une seconde gorge annulaire 100, de plus grande largeur que la gorge 96, ménagée sur sa surface périphérique.The drawer 38 also includes a second annular groove 100, of greater width than the groove 96, formed on its peripheral surface.

La gorge 100 a une largeur adaptée pour que, indépendamment de la position du tiroir 38, elle communique avec un conduit 110, ménagé dans le corps 12, raccordé aux chambres d'extrémité 42,44 et au second circuit de freinage C2 par l'intermédiaire des conduits 48-52.The groove 100 has a width adapted so that, independently of the position of the drawer 38, it communicates with a conduit 110, formed in the body 12, connected to the end chambers 42, 44 and to the second braking circuit C2 by the intermediate of conduits 48-52.

En position de repos du tiroir 38, telle que représentée à la figure 1, la première gorge annulaire 98 communique avec un conduit 102 raccordé par des moyens connus 104 au réservoir R1, et la seconde gorge annulaire 100 communique avec un conduit 106 ménagé dans le corps 12 et raccordé par des moyens connus 108 au réservoir R2.In the rest position of the drawer 38, as shown in FIG. 1, the first annular groove 98 communicates with a conduit 102 connected by known means 104 to the tank R1, and the second annular groove 100 communicates with a conduit 106 formed in the body 12 and connected by known means 108 to the reservoir R2.

Lorsque le tiroir 38 est déplacé axialement en position active de freinage, vers la gauche en considérant la figure 1, la première gorge 98 est isolée du conduit 102 de raccordement au réservoir R1, et la seconde gorge 100 est, d'une part, isolée du conduit de raccordement 106 au réservoir R2, et d'autre part mise en communication avec un conduit 112, ménagé dans le corps 12, raccordé par des moyens connus 114 à la source SP de liquide haute pression.When the slide 38 is moved axially in the active braking position, to the left when considering FIG. 1, the first groove 98 is isolated from the conduit 102 for connection to the reservoir R1, and the second groove 100 is, on the one hand, isolated of the connection conduit 106 to the reservoir R2, and on the other hand placed in communication with a conduit 112, formed in the body 12, connected by known means 114 to the source SP of high pressure liquid.

On décrira ci-dessous le fonctionnement du servofrein 10.The operation of the brake booster 10 will be described below.

Au cours du freinage, le conducteur actionne la pédale de frein 37 et déplace axialement vers la chambre centrale 40 le piston 36, par l'intermédiaire de la tringle de poussée 60.During braking, the driver actuates the brake pedal 37 and moves the piston 36 axially towards the central chamber 40, by means of the push rod 60.

Dans un premier temps, le tarage du ressort 72 précontraint porté par le piston 36 étant supérieur au tarage du ressort 84 de rappel du tiroir 38, les moyens 70 de poussée sollicitent le tiroir 38 à l'encontre de la force de rappel du ressort 84 et déplace celui-ci axialement vers la gauche en considérant la figure 1.Initially, the setting of the prestressed spring 72 carried by the piston 36 being greater than the setting of the spring 84 for returning the drawer 38, the thrust means 70 urge the drawer 38 against the return force of the spring 84 and displaces the latter axially to the left when considering FIG. 1.

Le déplacement du tiroir 38 provoque tout d'abord la fermeture simultanée des conduits 102,106 de raccordement aux réservoirs R1,R2 puis la mise en communication de la seconde gorge 100 avec le conduit 112 de raccordement à la source SP de liquide haute pression.The displacement of the drawer 38 firstly causes the simultaneous closing of the conduits 102, 106 for connection to the reservoirs R1, R2 and then the placing of the second groove 100 in communication with the conduit 112 for connection to the source SP of high pressure liquid.

Le réservoir R1 étant isolé de la chambre centrale 40, la pression du liquide contenu dans cette chambre et dans le premier circuit de freinage C1 augmente.The reservoir R1 being isolated from the central chamber 40, the pressure of the liquid contained in this chamber and in the first braking circuit C1 increases.

En position active de freinage, le tiroir 38 permet, d'une part d'alimenter en pression le second circuit de freinage, et d'autre part d'assister l'effort de freinage du conducteur.In the active braking position, the slide 38 allows, on the one hand to supply pressure to the second braking circuit, and on the other hand to assist the braking force of the driver.

En effet, la seconde gorge 100 étant alimentée en liquide haute pression, la pression du liquide contenu dans le second circuit de freinage C2, communiquant avec la gorge 100, augmente.Indeed, the second groove 100 being supplied with high pressure liquid, the pressure of the liquid contained in the second braking circuit C2, communicating with the groove 100, increases.

Par ailleurs, la pression du liquide dans le second circuit de freinage C2 est également celle du liquide contenu dans les chambres d'extrémités 42 et 44 communiquant avec le circuit C2. La pression du liquide de la chambre 42 agit sur le piston 36, dans le sens du freinage, de manière à amplifier l'effort fourni par le conducteur sur la pédale de frein.Furthermore, the pressure of the liquid in the second braking circuit C2 is also that of the liquid contained in the end chambers 42 and 44 communicating with the circuit C2. The pressure of the liquid in the chamber 42 acts on the piston 36, in the direction of braking, so as to amplify the force supplied by the driver on the brake pedal.

La largeur et la position des deux gorges périphériques 98,100 du tiroir 38 sont adaptées pour que, d'une part la course du tiroir permettant d'isoler les conduits 102 et 106, et d'autre part la course du tiroir permettant de mettre en communication la seconde gorge 100 avec le conduit 112, soient très faibles. De cette façon, après un très faible déplacement du tiroir, ce dernier est en équilibre sous l'action de forces qui se compensent. Ces forces sont d'une part, du côté de la chambre 44, la force due à la pression du liquide du second circuit de freinage C2 et la force de rappel du ressort 84, et d'autre part, du côté de la chambre 40, la force due à la pression du liquide du premier circuit de freinage C1 et la force de poussée du ressort 72.The width and the position of the two peripheral grooves 98,100 of the drawer 38 are adapted so that, on the one hand the stroke of the drawer making it possible to isolate the conduits 102 and 106, and on the other hand the stroke of the drawer making it possible to put in communication the second groove 100 with the conduit 112, are very weak. In this way, after a very small displacement of the drawer, the latter is in equilibrium under the action of compensating forces. These forces are on the one hand, on the side of the chamber 44, the force due to the pressure of the liquid from the second braking circuit C2 and the return force of the spring 84, and on the other hand, on the side of the chamber 40, the force due to the pressure of the liquid from the first circuit brake C1 and spring 72 pushing force.

On notera donc que les pressions hydrauliques des deux circuits de freinage C1,C2 sont identiques à la différence de tarage près des deux ressorts 72,84.It will therefore be noted that the hydraulic pressures of the two braking circuits C1, C2 are identical to the calibration difference near the two springs 72, 84.

De préférence, la différence de tarage des deux ressorts 72,84 est telle que la différence de pression de part et d'autre du tiroir 38 n'excède pas 2 bar en cours de freinage intense.Preferably, the calibration difference of the two springs 72, 84 is such that the pressure difference on either side of the slide 38 does not exceed 2 bar during intense braking.

Au cours du freinage, le déplacement du piston 36 est proportionnel à la consommation en liquide du premier circuit de freinage C1, c'est-à-dire proportionnel au déplacement de liquide dû à la course des pistons montés de façon classique dans les organes de freinage disposés au voisinage des roues du véhicule et alimentés par ce circuit.During braking, the displacement of the piston 36 is proportional to the liquid consumption of the first braking circuit C1, that is to say proportional to the displacement of liquid due to the stroke of the pistons conventionally mounted in the organs of braking arranged in the vicinity of the vehicle wheels and supplied by this circuit.

On notera que pendant toute l'opération de freinage le ressort 62 de rappel du piston 36 est comprimé.Note that during the entire braking operation, the spring 62 for returning the piston 36 is compressed.

Lorsque le conducteur cesse de freiner et relâche la pédale de frein 37, le piston 36 est sollicité vers sa position de repos par le ressort 62, la pression du liquide contenu dans la chambre centrale 40 diminue et le tiroir 38 est également sollicité vers sa position de repos.When the driver stops braking and releases the brake pedal 37, the piston 36 is biased towards its rest position by the spring 62, the pressure of the liquid contained in the central chamber 40 decreases and the drawer 38 is also biased toward its position rest.

Le déplacement du tiroir 38 en sens inverse de celui décrit lors de l'opération de freinage provoque la fermeture du conduit 112 de raccordement à la source de liquide haute pression, les ouvertures simultanées des conduits 102,106 de raccordement aux réservoirs R1,R2 et par conséquent la chute des pressions hydrauliques dans les deux circuits de freinage C1,C2.The displacement of the slide 38 in the opposite direction to that described during the braking operation causes the closing of the conduit 112 for connection to the source of high pressure liquid, the simultaneous openings of the conduits 102, 106 for connection to the tanks R1, R2 and consequently the drop in hydraulic pressures in the two braking circuits C1, C2.

On décrira maintenant un piston 36 et un tiroir 38 de régulation de pression suivant un autre mode de réalisation, en regard de la figure 2.We will now describe a piston 36 and a pressure regulating slide 38 according to another embodiment, with reference to FIG. 2.

Sur cette figure les éléments analogues à ceux de la figure 1 sont désignés par des références identiques.In this figure, elements similar to those of FIG. 1 are designated by identical references.

Dans ce cas, les moyens élastiques de poussée 70 comprennent un ressort 72 porté par un support 78A formant tube, maintenu par une de ses extrémités sur le piston 36, coaxialement à ce dernier.In this case, the elastic pushing means 70 comprise a spring 72 carried by a support 78A forming a tube, held by one of its ends on the piston 36, coaxial with the latter.

L'extrémité de fixation du support 78A comporte une collerette 116 et est engagée jusqu'au fond d'un évidement axial 117 ménagé dans l'extrémité du piston 36 en regard de la chambre centrale 40.The fixing end of the support 78A comprises a flange 116 and is engaged to the bottom of an axial recess 117 formed in the end of the piston 36 opposite the central chamber 40.

Un embout 118 est vissé sur l'extrémité libre du support 78A. Cet embout 118 comporte une tête circulaire 120 d'un diamètre supérieur au diamètre externe du support 78A de manière à former un épaulement d'extrémité du support 78A.A tip 118 is screwed onto the free end of the support 78A. This nozzle 118 comprises a circular head 120 with a diameter greater than the external diameter of the support 78A so as to form an end shoulder of the support 78A.

Le ressort 72 est précontraint entre deux sièges, le premier étant formé par la collerette 116 du support 78A et le second étant formé par une douille 122, munie à une de ses extrémités d'une collerette 124 destinée à coopérer avec le ressort, montée coulissante sur le support 78A.The spring 72 is prestressed between two seats, the first being formed by the flange 116 of the support 78A and the second being formed by a sleeve 122, provided at one of its ends with a flange 124 intended to cooperate with the spring, slidingly mounted on support 78A.

La collerette 124 est par ailleurs destinée à coopérer avec un épaulement 126 ménagé dans la surface interne du trou axial 94 du tiroir 38.The flange 124 is also intended to cooperate with a shoulder 126 formed in the internal surface of the axial hole 94 of the drawer 38.

La course de la douille 122 est limitée à l'extrémité libre du support 78A par l'épaulement formé par la tête 120 de l'embout 118.The stroke of the sleeve 122 is limited to the free end of the support 78A by the shoulder formed by the head 120 of the end piece 118.

Le support 78A et l'embout 118 comportent des perçages 128,130 permettant le passage de l'huile de frein entre le trou 94 et la chambre centrale 40.The support 78A and the end piece 118 have holes 128,130 allowing the passage of the brake oil between the hole 94 and the central chamber 40.

Comme dans le premier mode de réalisation, le trou 94 du tiroir 38 forme un logement pour le support 78A des moyens de poussée 70.As in the first embodiment, the hole 94 of the drawer 38 forms a housing for the support 78A of the pushing means 70.

Le fonctionnement du piston 36 et du tiroir 38 est analogue au fonctionnement décrit ci-dessus pour le premier mode de réalisation.The operation of the piston 36 and of the drawer 38 is analogous to the operation described above for the first embodiment.

L'invention ne se limite pas aux modes de réalisation décrits.The invention is not limited to the embodiments described.

En particulier, les deux réservoirs de la centrale hydraulique peuvent être remplacés par un réservoir unique.In particular, the two tanks of the hydraulic unit can be replaced by a single tank.

L'invention comporte de nombreux avantages.The invention has many advantages.

Elle permet de commander deux circuits de freinage complètement indépendants, avec une course de pédale relativement faible correspondant au déplacement de liquide dans un seul de ces deux circuits.It makes it possible to control two completely independent braking circuits, with a relatively small pedal stroke corresponding to the displacement of liquid in only one of these two circuits.

Le tiroir de régulation de pression permet d'isoler simultanément les conduits de raccordement aux réservoirs des circuits de freinage et par conséquent d'obtenir une montée en pression simultanée dans les deux circuits de freinage lors de l'actionnement de la pédale de frein.The pressure regulation drawer simultaneously isolates the connection lines to the brake circuit reservoirs and therefore achieves a simultaneous pressure rise in the two brake circuits when the brake pedal is actuated.

Le servofrein est facile à fabriquer étant donné que les alésages dans lesquels coulissent le piston et le tiroir de régulation de pression sont coaxiaux et de diamètres sensiblement identiques. Ces alésages peuvent être percés en une seule opération d'usinage. Cependant les opérations de finition peuvent être effectuées différemment selon que l'alésage est destiné à recevoir le piston ou bien le tiroir de régulation de pression.The brake booster is easy to manufacture since the bores in which the piston and the pressure regulating slide slide are coaxial and of substantially identical diameters. These bores can be drilled in a single machining operation. However, the finishing operations can be carried out differently depending on whether the bore is intended to receive the piston or the pressure regulating slide.

Claims (8)

  1. A hydraulic actuating device for a braking installation in a motor vehicle comprising two hydraulic braking networks (C1, C2), the device being fitted with means for hydraulic amplification of the braking force, of the type comprising a body with a piston (36) actuated by a brake pedal (37) and slidably mounted in a first bore (14) provided in the body (12), [and] a pressure-regulating slide valve (38) slidably mounted in a second bore (16) provided in the body (12) coaxially with the first bore (14), the adjacent ends of the bores (14, 16) communicating with one another, the piston (36) and the slide valve (38) firstly defining between their adjacent ends a central pressure chamber (40) communicating with a first braking network (C1) and secondly defining at their remote ends two end chambers (42, 44) which communicate with one another and with the second braking network (C2), the slide valve (38) being displaceable between an idle position towards which it is resiliently returned and in which it brings about communication of the end chambers (42, 44) with a reservoir (R2) of fluid at standard pressure, and a regulating position in which it brings about communication of the end chambers (42, 44) and the second braking network (C2) with a source (SP) of high-pressure fluid, the pressure thereof being greater than the standard pressure, characterized in that the pressure-regulating slide valve (38) comprises means (94 - 98) for bringing about communication of a reservoir (R1) of fluid at standard pressure with the central chamber (40) when the slide valve (38) is in its idle position.
  2. A device according to claim 1, characterised in that the communication means comprise a substantially axial hole (94) provided in the slide valve (38) and opening into the central chamber (40) and connected, by at least one substantially radial bore (96) provided in the slide valve (38), to an annular throat (98) which is provided in the peripheral surface of the slide valve (38) and is intended to be brought into communication with a conduit (102) which is connected to the reservoir (R1) for fluid at standard pressure, when the slide valve (38) is in its idle position.
  3. A device according to claim 1 or 2, characterised in that the piston (36) comprises resilient push means (70) intended to stress the slide valve (38) against the means (84) for returning the said slide valve (38) into its idle position.
  4. A device according to claim 3, characterised in that the resilient push means (70) comprise a pre-stressed spring (72) of a rating greater than the rating of a spring (84) in the means for returning the slide valve (38) into its idle position.
  5. A device according to claim 4, characterised in that the pre-stressed spring (72) is arranged between two seats (74, 76), the first seat (74) being rigid with the piston (36) and the second seat (76) being slidably mounted on a support forming a rod (78) which is rigid with the piston (36), the free end of the rod (78) comprising a flange (80) intended to co-operate by abutment with the sliding seat (76) in order to maintain the pre-stressing of the spring, the sliding seat (76) co-operating with a shoulder (83) provided in the peripheral outer surface of the slide valve (38).
  6. A device according to claim 4, characterised in that the pre-stressed spring (72) is arranged between two seats (116, 124), the first seat being rigid with the piston (36) and formed at one end of a tubular support (78A), the second seat (124) being slidably mounted on the said tubular support, the free end of the support (78A) comprising an end piece (118) forming a stop device and intended to co-operate with the sliding seat (124) in order to maintain the pre-stressing of the spring (72), the sliding seat (124) co-operating with a shoulder (126) provided in the surface of the slide valve (38) delimiting the substantially axial hole (94).
  7. A device according to claim 5 or 6, characterised in that the substantially axial hole (94) in the slide valve (38) forms a housing for the support (78; 78A) of the pre-stressed spring, whilst the slide valve (38) and the piston (36) are displaced relative to one another during a braking operation.
  8. A device according to any one of claims 1 to 7, characterised in that the two coaxial bores (14, 16) are of substantially identical diameter.
EP19930402392 1992-10-26 1993-09-30 Hydraulic command device for brake system of a vehicle with two hydraulic brake circuits Expired - Lifetime EP0595670B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9212747 1992-10-26
FR9212747A FR2697216B1 (en) 1992-10-26 1992-10-26 Hydraulic actuation device for the braking system of a motor vehicle comprising two hydraulic braking circuits.

Publications (2)

Publication Number Publication Date
EP0595670A1 EP0595670A1 (en) 1994-05-04
EP0595670B1 true EP0595670B1 (en) 1995-12-06

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19930402392 Expired - Lifetime EP0595670B1 (en) 1992-10-26 1993-09-30 Hydraulic command device for brake system of a vehicle with two hydraulic brake circuits

Country Status (3)

Country Link
EP (1) EP0595670B1 (en)
DE (1) DE69300965T2 (en)
FR (1) FR2697216B1 (en)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1468014A (en) * 1973-10-25 1977-03-23 Dewandre Co Ltd C Hydraulic braking systems
FR2480371A1 (en) * 1980-04-15 1981-10-16 Ferodo Sa ASSISTED HYDRAULIC CONTROL, IN PARTICULAR FOR CLUTCHES AND BRAKES
FR2480690A1 (en) * 1980-04-16 1981-10-23 Dba HYDRAULIC SERVO BRAKE
GB8502130D0 (en) * 1985-01-29 1985-02-27 Lucas Ind Plc Servo-assisted master cylinder assemblies

Also Published As

Publication number Publication date
FR2697216A1 (en) 1994-04-29
DE69300965T2 (en) 1996-05-23
DE69300965D1 (en) 1996-01-18
FR2697216B1 (en) 1995-01-27
EP0595670A1 (en) 1994-05-04

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